Experimental investigation and thermodynamic modeling of the Ni-Pr system

The Ni-Pr system is investigated via experiments and thermodynamic modeling. In the experimental part, five alloys with compositions of Ni-96 at.% Pr, Ni-85 at.% Pr, Ni3Pr, Ni5Pr and Ni-5 at.% Pr were prepared by arc melting pure Ni and Pr slugs and annealing the alloys at 500 °C for 2 weeks. The annealed alloys were then subjected to differential thermal analysis (DTA) measurements. The decomposition temperatures of Ni7Pr2 (1162 °C), Ni3Pr (1029 °C), Ni2Pr (921 °C), dhcp (Pr) (780 °C), the eutectic reaction temperature of liquid  ↔  fcc (Ni) + Ni5Pr (1280 °C) and the congruent melting point of Ni5Pr (1385 °C) were determined by DTA, respectively. In the modeling part, the available phase equilibrium and thermodynamic data in the Ni-Pr system were analyzed by using thermodynamic models for the Gibbs energies of individual phases. An optimal set of thermodynamic parameters was obtained using WinPhad software. The calculated phase equilibria and thermodynamic properties from the model parameters were compared to the corresponding experimental data and good agreement was obtained.